Abstract
Osteoarthritis (OA) is a common joint disorder found mostly in elderly people. The role of mechanical behavior in the progression of OA is complex and remains unclear. The stress-relaxation behavior of human articular cartilage in clinically defined osteoarthritic stages may have importance in diagnosis and prognosis of OA. In this study we investigated differences in the biomechanical responses among human cartilage of ICRS grades I, II and III using polymer dynamics theory. We collected 24 explants of human articular cartilage (eight each of ICRS grade I, II and III) and acquired stress-relaxation data applying a continuous load on the articular surface of each cartilage explant for 1180 s. We observed a significant decrease in Young’s modulus, stress-relaxation time, and stretching exponent in advanced stages of OA (ICRS grade III). The stretch exponential model speculated that significant loss in hyaluronic acid polymer might be the reason for the loss of proteoglycan in advanced OA. This work encourages further biomechanical modelling of osteoarthritic cartilage utilizing these data as input parameters to enhance the fidelity of computational models aimed at revealing how mechanical behaviors play a role in pathogenesis of OA.
Highlights
Articular cartilage is the tissue that covers the bone ends in diarthroidal, synovial joints
The mechanical properties of articular cartilage depend on the structural integrity of the constituents of the matrix composed mainly of collagen, proteoglycan (PG) and water [1]
In addition to the biochemical and structural changes, the biomechanical properties of the articular cartilage have been shown to evolve with the stage of OA [7,8,9,10,11]
Summary
Articular cartilage is the tissue that covers the bone ends in diarthroidal, synovial joints. Our previous studies have shown biochemical and structural changes in early stage of osteoarthritic cartilage [4,5,6]. In addition to the biochemical and structural changes, the biomechanical properties of the articular cartilage have been shown to evolve with the stage of OA [7,8,9,10,11]. Current understanding about the changes in biomechanical properties and its consequences in cartilage degradation during progression of OA is limited. Knowledge about the changes in mechanical behavior of articular cartilage at various stages of OA can help in understanding the mechanisms of disease progression
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